The DBCACNX extension applies only to the explicit Connect, or an implicit Connect for the RunStartup, Initiate Request, or Initiate request With Protocol-function, and only when the Connect-type option specifies a combined logon and connect. Use of the Connection-extension will be rejected if the Connect-type option specifies a separate logon and run. When used, it should be pointed to by the Extension-pointer DBCAREA field before invoking the function. The Extension-pointer should be zeroed after the function to prevent subsequent functions from attempting to use it. It is ignored by other DBCHCL functions.
The prologue for the Assembler, COBOL, C, and PL/I, mappings of the DBCACNX provides language-dependent information in constructing an extension and should be consulted.